End brushes are often-manufactured utilizing rings, sleeves, pins or keys as anchors to secure the bristle fill material bundle in the holder with the fill material bundles being folded as a hairpin in the cup of the holder. This results in a non-uniform distribution and density of the fill material and also normally requires a secondary operation such as trimming of the brush face. Such internal anchors can in and of themselves affect the dynamic balance or stability of the tool quite apart from causing non-uniform distribution of the fill material.
Samples of end brushes or tools using mechanical anchors or keys may be seen in prior U.S. Pat. No. 2,982,983 to Peterson. Other examples are seen in Benyak U.S. Pat. Nos. 2,449,158 and 2,755,496, Less U.S. Pat. No. 3,106,739, Peterson U.S. Pat. No. 2,421,647 and Tilgner U.S. Pat. No. 3,237,234.
The brush making methods of these prior patents are such that it is difficult to distribute properly the fill material and also any insert or key such that good dynamic balance is obtained.
It is therefore desirable to have a method and end brush made by that method which will achieve good dynamic balance and which can be made quickly, automatically, and efficiently.